This application claims the priorities of German application Nos. 199 19 437.8, filed Apr. 29, 1999, and 199 42 040.8, filed Sep. 3, 1999, the disclosures of which are expressly incorporated by reference herein.
The present invention relates to an arrangement for preventing the squealing of a disk brake including a particular brake disk, with friction rings, and brake linings. The brake linings have a partial circumference length which relates to an approximately mean circumference of the brake disk. An imposed natural oscillation mode of the brake disk with n-nodes is obtained. Slots are provided in the friction rings.
German Patent Document DE 195 07 102 A1 relates to a disk brake which is tuned such that squealing noises during a braking operation are eliminated or reduced by way of adjacent brake linings. This takes place by establishing a certain ratio of the brake lining length to the brake disk circumference.
German Patent Document DE 40 41 010 relates to an arrangement for preventing the squealing of a disk brake. In this arrangement, the friction linings, which consist of a semi-metallic or asbestos-free material, are pressed onto a disk rotor or onto a brake disk for carrying out braking. The rotor is divided such that the second order resonance frequency of the longitudinal oscillation of the rotor is larger than 15 kHz. Division of the disk rotor takes place by way of slots which are arranged on the inside and the outside of the rotor.
It is an object of the invention to provide a disk brake in which the occurrence of squealing noises is prevented by a detuning of the natural frequency mode of the brake system.
According to the invention, this object is achieved by providing the friction rings of the brake disk, in at least one surface area of at least one friction surface thereof, with a local weakening of the section modulus such that a detuning node oscillation which is unequal to a natural vibration mode of the brake disk can be achieved. The nodes are formed from the ratio n=u/L, wherein u is a median brake disk circumference and L is a partial circumference length of the brake linings. Additional advantageous characteristics are also claimed.
Principal advantages achieved by the invention include detuning the natural oscillation behavior of existing brakes in the event of a squealing action such that brake squealing is reduced or eliminated.
According to the invention, this is essentially achieved by having a local weakening of the section modules xe2x80x9cWxe2x80x9d in at least one surface area of the friction surfaces of the friction ring of a solid brake disk, or of the friction rings of an internally ventilated brake disk, such that a detuning natural oscillation, which is unlike the natural oscillation mode of the brake disk with the oscillation node xe2x80x9cWxe2x80x9d, can be achieved.
The local weakening or weakenings of the section modulus in one or both friction rings of the brake disk preferably are provided by one or several slots which separate the friction ring or rings and extends or extend from the brake disk center to approximately the outer edge or edges of the friction ring or rings.
A resulting detuning of the natural oscillation mode of the brake disk is provided by correspondingly arranged and dimensioned slots in both friction rings or in one friction ring in order to achieve locally reduced section moduli in one or several areas of the friction rings of the brake disk.
According to one embodiment of the invention, the slots may be arranged between the cooling ducts of the brake disk as well as on the ribs. Furthermore, the slots may be provided in the outer friction ring as well as in the inner friction ring or in both friction rings. In addition, the slots can also be provided in an alternating sequence in the outer and the inner friction rings.
Since each of the slots may separate parts of the friction rings, special links may be required by way of ribs, such as double ribs, which are situated closely side-by-side. When the brake rings have opposed slots, the ribs, which are situated side-by-side, are connected with one another by way of a transverse web.
According to the invention, the courses of the slots in the friction rings can be adapted to the courses of the ribs of the cooling ducts so that radial and diagonally extending slots are used which extend on the rib as well as between the ribs. It is also conceivable to arrange slots oppositely diagonally to the ribs and so as to cross over the ribs.
If a slot is arranged in the rib of the cooling duct, a wide rib is usually required so that the rib still results in sufficient stiffness. The number of ribs which are wider than the other ribs is selected corresponding to the requirements for preventing brake squealing. Thus, one wider rib or several wider ribs may be required. The width of the slot should be as narrow as possible so that the brake disk is not stressed by unnecessary rubbing effects. For this reason, it is also advantageous for the slot to have chamferings in the friction surface of the brake disk.
In every case, a locally reduced section modulus on the brake disk or in the friction rings achieves a detuning of the original natural oscillation mode of the brake disk. The local reduced section modulus achievable by the slots is preferably arranged at the same mutual distance and is designed unequal to the modes of the natural oscillation mode so that, for example, with a six-node oscillation, weakening of the brake disk occurs at four points.